Digital clay apparatus and method

ABSTRACT

A system and method for controlling the surface and/or volume of a digital clay device is provided. One embodiment, among others, is a method comprising the following steps: determining a desired position of a skeleton structure portion residing in the digital clay device, determining a volumetric change of fluid residing in a fluid cell, the determined volumetric change corresponding to the determined desired position of the skeleton structure portion, opening a valve so that the fluid flows through the valve thereby causing the determined volumetric change of the fluid, and adjusting a position of the skeleton structure portion corresponding to the desired position of the skeleton structure portion, the position adjustment caused by a force generated by the fluid cell on the skeleton structure portion when the volume of the fluid cell changes in response to the determined volumetric change of the fluid residing in the fluid cell.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of copending U.S. utility applicationentitled, “DIGITAL CLAY APPARATUS AND METHOD,” having Ser. No.10/164,888, filed Jun. 7, 2002 now U.S. Pat. No. 2,836,736, which isentirely incorporated herein by reference.

This document claims priority to and the benefit of the filing date ofco-pending commonly assigned Provisional Application entitled, “DIGITALCLAY FOR SHAPE INPUT TO AND DISPLAY FROM A COMPUTER,” filed Jun. 8,2001, and accorded Ser. No. 60/296,938. The foregoing pendingprovisional application is hereby incorporated herein by reference inits entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The U.S. Government may have a paid-up license in this invention and theright in limited circumstances to require the patent owner to license toothers on reasonable terms as provided for by the terms of Contract No.IIS-0121663, awarded by the National Science Foundation.

TECHNICAL FIELD

The present invention is generally related to haptic interface devicesand, more particularly, is related to a system and method forcontrolling the shape of and/or for receiving information pertaining toa surface and/or a volume of a digital clay device.

BACKGROUND OF THE INVENTION

Significant prior research has been performed in the area of hapticinterfaces. Several haptic-based interaction systems have been developedand used for a variety of applications, including molecular dynamicssimulation and steering, manipulation of nano-materials, surgicaltraining, virtual prototyping, and digital sculpting.

Early haptic interface systems utilized a robot arm, both as a sixdegree-of-freedom input device as well as a force feedback outputdevice, providing the user with a tactile perception of molecular forcesand torques. Since then, alternative force-feedback devices withmultiple degrees of freedom have been proposed. These approaches providean intuitive interface for the manipulation of rigid bodies subjected toinertial, contact, or other forces. They are, however, significantlyless convenient for sensing and altering the shape of curves andsurfaces.

These haptic devices and techniques focus on force feedback, whichassists the user in gauging the effort required to be exerted on thesurface in order to achieve the desired shape alteration. This approachmay also be used to provide information about the stiffness or densityof the surface. In addition, such haptic approaches have been applied tothe exploration of a field in a volume or even of fluid dynamics.However, these approaches do not provide sufficient tactile feedbackregarding the shape of the surface.

Running the tip of a computer cursor over the virtual surface has beensuggested as a means for “haptic surface rendering” and have beenextended to real-time detection of contacts when manipulating an objectwith six degrees of freedom. The contact forces may be computed usingthe concept of “virtual proxy”.

Such approaches, based on exploration of a surface with the tip or sideof a stylus, produce forces that would result from contact, palpation,or stroking actions. These forces may reveal surface anomalies orattract the attention of the designer to small, high-spatial-frequencyfeatures that may have been more difficult to detect visually. However,stylus-based approaches are far from exploiting the natural ability of adesigner to feel a surface by touching it with a wider area of the hand.

Interfaces involving touch have used gloves, manipulators controlling astylus held by the hand, and arrays of actuators to depict a surface.They attempt to supply sensations received through our various touch andkinesthetic receptors, often broken into several regimes. Vector macroforces are at the gross end of that scale and are readily displayed bymanipulator-like haptic devices. Vibrations are by nature a scalar fieldand may be distributed widely over the surface of the skin. Theamplitude and frequency are noticeable but not the direction. The mostdifficult to display are small shapes, for which arrays of stimulatorsare necessary. To achieve both kinesthetic and tactile sensationssimultaneously the combination of a haptic manipulator and a tactilearray is currently required.

A stylus grasped by a user is one way to explore a haptic environment ina pointwise fashion. If the stylus is attached to a manipulator,interaction forces can be generated which represent interaction of thestylus with a virtual world. Available pointwise haptic displays allowforces and moments to be fed back to the user in two to six degrees offreedom and are well suited to provide the kinesthetic portion of ahaptic experience. Haptic mice enable the user to feel the transition ofthe cursor between different regions of the screen. These hapticmanipulators open new possibilities of interfacing, but are comparableto displaying a picture to a viewer one pixel at a time. Hapticmanipulators must provide spatial relationships only through temporalsequencing, greatly compromising their efficiency. Sample rates of 1000Hz are typical with forces controlled at 30 Hz or more for adequatedisplay of features such as a breast tumor.

It is necessary to provide a totally synthetic view of the hand in theenvironment if haptics are coordinated with vision. Viewing the stylusand its device provides no supporting optical illusion. Anotherdisadvantage of the numerous devices is that the ratio of the smallestto the largest displayable force is difficult to expand. When the handshould be moving unimpeded, it still must exert a force to move thedevice forward. This problem has been only partially overcome byutilizing a servomechanism based on the position of the hand to avoidcontact (i.e., achieve 0 force) except when contact should be displayed.

SUMMARY OF THE INVENTION

The present invention provides a system and method for controlling thesurface and/or volume of a digital clay device. Briefly described, inarchitecture, one embodiment is a method comprising the following steps:determining a desired position of a skeleton structure portion residingin the digital clay device, determining a volumetric change of a fluidresiding in a fluid cell, the determined volumetric change correspondingto the determined desired position of the skeleton structure portion,opening a valve so that the fluid flows through the valve therebycausing the determined volumetric change of the fluid residing in thefluid cell, and adjusting a position of the skeleton structure portioncorresponding to the desired position of the skeleton structure portion,the position adjustment caused by a force generated by the fluid cell onthe skeleton structure portion when the volume of the fluid cell changesin response to the determined volumetric change of the fluid residing inthe fluid cell.

Another embodiment of the invention is a method comprising the followingsteps: determining an initial position of a skeleton structure portionresiding in the digital clay device, sensing a pressure change in afluid cell, the pressure change corresponding to an external forceapplied to an exterior portion of the digital clay device, opening avalve in response to the sensed pressure change such that fluid residingin the fluid cell exits the fluid cell, sensing flow of the fluidthrough the valve, closing the valve when the sensed pressure is reducedto at least a predefined value, the reduced pressure resulting from theexit of fluid from the fluid cell, such that flow of the fluid throughthe valve stops, determining a volumetric change in the fluid from thesensed flow after the valve is closed, and determining a change in theposition of the skeleton structure portion based upon the determinedvolumetric change.

Another embodiment of the invention comprises a processor system and aplurality of cells, each one of the plurality of cells furthercomprising at least one fluid cell, the fluid cell configured to hold afluid, at least one valve, the valve controlled by the processor system,and at least one sensor coupled to the valve, the sensor configured tosense flow of a fluid through the hysteric valve such that a volumetricchange in the fluid is determinable by the processor system.

Other systems, methods, features, and advantages of the presentinvention will be or become apparent to one with skill in the art uponexamination of the following drawings and detailed description. It isintended that all such additional systems, methods, features, andadvantages be included within this description, be within the scope ofthe present invention, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding partsthroughout the several views.

FIG. 1A is a block diagram of a table top embodiment of a digital claydevice according to the present invention.

FIG. 1B is a block diagram of a hand held embodiment of a digital claydevice according to the present invention.

FIG. 2 is a block diagram of an embodiment of a cell.

FIG. 3 is a block diagram of an alternative embodiment of a cell.

FIGS. 4A–G illustrate exemplary cell bladders and/or skeleton structureembodiments.

FIGS. 5 and 6 are flowcharts illustrating processes used by anembodiment of the digital clay device to adjust the position of askeleton structure portion.

FIG. 7 is a flow chart illustrating processes used by an embodiment ofthe digital clay device to sense the position of a skeleton structureportion.

DETAILED DESCRIPTION

The present invention provides a system and method for controlling theshape of and/or for receiving information pertaining to a surface, or avolume, or both, of a digital clay device. When operating in one mode,the surface or volume is detected and determined by the presentinvention, a digital clay device, as described herein, such that aprocessing system embodiment digitally computes attributes relating to astate of the digital clay device surface and/or volume. When the presentinvention is operating in a shape and/or volume controlling mode, theprocessing system embodiment digitally computes desired attributesrelating to the surface, or volume, or both, and instructs the digitalclay device to deform to the desired attributes. Determination ofattributes of the digital clay device surface and/or volume, and/orcontrol of the digital clay device surface and/or volume, may be donestatically or dynamically.

In engineering, art, science, medicine and/or communication, shape is akey feature for product design, sculpting, interpreting and/orunderstanding complex data and the relation between geometricalfeatures. Also, many in our society depend on touch as a substitute forsight and are increasingly disenfranchised in visually dominatedelectronic communication in school and in everyday life. An effectivemeans to specify (input) and display shapes to/from the computer isprovided by the present invention, a digital clay device.

Natural clay is ideally a continuous medium. That is, it ideally hasinfinite resolution. Although digital clay is actually spatiallydiscrete, with respect to human perception, the micro-sized nature of anindividual cell of the digital clay device achieves a virtual infiniteresolution with respect to human visual and tactile perception. Thus,digital clay, in one embodiment, has a texture and feel similar tonatural clay.

One embodiment of a digital clay device is a distributed input/displaydevice whose surface and/or volume can be shaped by a human user andimmediately acquired by a processing system. Or, the surface and/orvolume can be shaped by the processing system for the human to examine.Like ordinary clay, digital clay allows a surface or volume to betouched, reshaped with pressure and seen by the user in truethree-dimensional form. Unlike ordinary clay, digital clay also providesparameters to the processing system that will represent the shape forthe surface and/or volume to the processing system for further analysis,storage, replication, communication and/or modification. Accordingly,digital clay allows the processing system to command its shape and/orvolume, providing two-way communication between the processing systemand the user.

The digital clay employs a fluid flow from a plurality of micro-electromechanical systems (MEMS) valves to and from a large array of bladders.In one embodiment, the bladder array allows any variety of shapes(surface or volume) for a parallel-actuated structure covered with anelastomeric external skin. Stereolithography enables the efficientproduction of the actuated structure. Measurement by sensors coupled tothe MEMS valves allows feedback control of the MEMS valves, therebyenabling the processing system to read or command the shape of thedigital clay device.

When operating in a mode of controlling a shape and/or volume, thesurface and/or volume of the digital clay is extended (or retracted) bythe processing system controlled array of MEMS valves that allowpressurized fluid to flow into a massively parallel-actuated structurehaving bladders and a skeleton, thereby selectively extending (orretracting) selected portions of the surface and/or volume. The MEMSvalves, in one embodiment, are located on a backplate and fluid is“piped” into the bladders, as described herein according to the presentinvention. MEMS valves move microscopically to allow fluid flowinto/from a controlled bladder. Bladder fluid changes cause macroscopicdisplacements in the surface or volume of the digital clay device. Withcoordination of numerous MEMS valves, the characteristics of the digitalclay surface or volume is controlled.

When operating in a mode of detecting and determining a shape and/orvolume, a user applies an external force to the surface and/or volume ofthe digital clay device. Fluid is expelled from the bladders and throughan array of MEMS valves. Shaping digital clay is fundamentally a removaland/or relocation process. Embedded sensors coupled to the MEMS valvesallow actuator displacement and/or other parameters to be senseddirectly, or computed from, sensed values. Accordingly, the sensorsdetect fluid changes in the bladders. Thus, when a force is applied tothe digital clay surface, the MEMS valves are selectively allowed toopen to avoid singular conditions internal to the digital clay.

A first digital clay embodiment is a “chunk of clay” that sits on atable top. Another embodiment is held by a user. Applications for thetable top embodiment include, but are not limited to, terrain models,conceptual shape models of engineered products (e.g., cars), stylingmodels for architecture and industrial design, and artistic sculpture.For the user held embodiment, applications include, but are not limitedto, animation/claymation characters, conceptual design models ofhand-held engineered devices, toys, and medical models of organs (shapeand “feel” of one or more organs).

FIG. 1A is a block diagram of a table top embodiment of a digital claydevice 100 according to the present invention. The digital clay deviceincludes a backplate 102, a plurality of cells 104 configured into apredetermined three-dimensional cell array 106, a digital clay surface108, and a processing system 110. For convenience, only a portion of thebackplate 102, digital clay array 106 and digital clay surface 108 isillustrated in FIG. 1A. The shape, size, elasticity and texture of thedigital clay surface 108 can be selected to suit a particularembodiment.

In various embodiments, each actuator comprises a discretefluidically-inflatable cell that is connected to two common pressurizedreservoirs (within a base) through a two-way miniature valve integratedwith a pressure sensor. Included in such embodiments is a backplatebearing passive or active valves that allow either filling or drainingof the cell into their respective reservoirs, and also bearing thepressure sensors that measure the pressure drop across each valve.

In an exemplary embodiment, the backplate consists of a rigid basebearing a dense array of individual modular elements, wherein eachmodule possesses means for a fluidic connection to the actuator cells inthe volume of the clay. At a minimum, each module comprises threecomponents: a pressure sensor, a passive or active hysteretic valve (seebelow), and control logic/electrical interconnect. Hysteretic valves arevalves that do not conduct fluid in either direction until a thresholdpressure drop, significantly greater than zero, is exceeded. Suchhysteretic valves are required in the digital clay application to ensurethat the clay, once deformed into a specific shape either by the user orby computer commands, remains in that position until a further commandis received. A hysteretic valve can be turned ‘on’ in one of two ways:either the threshold pressure in either direction is exceeded (passiveoperation), or the hysteresis pressure is lowered to zero by someexternal, active control means (active operation). Passive operationwould be primarily used when the user is ‘sculpting’ a shape out of thedigital clay. Active operation would primarily be used when, undercomputer control, the digital clay is being programmed to assume aspecific shape.

Each module of the backplate 102 will be dedicated to and in fluidiccommunication with a fluidic cell 104, which will provide actuationpower and pressure sensing to the scaffolding in the volume of the clay.Since each cell 104 will contain a microfluidic line, formed bylamination (see below), between its volume and a modular element on theunderlying substrate, the substrate will contain a two-dimensionalprojection of the three-dimensional volume of actuating cells 104. Eachmodule (valve and pressure sensor) will therefore allow control andmeasurement of the pressure in each fluidic cell 104. MEMS technologymay be in this application for two reasons. First, a dense array ofphysically small sensors and actuators are required (the devices must bephysically small due to the three-to-two dimensional projection thatoccurs on the surface of the substrate). Second, all of the electricalwiring as well as attachment pads for multiplexing and interface siliconchips can be lithographically formed on the substrate simultaneouslywith the sensors and actuators. It should be noted that no MEMSstructures are required to undergo large displacements or generatelarge, macroscopic forces in the operation of the digital clay. All ofthe ‘macroscopic’ force required originates in the fluidic reservoir 224(FIG. 2). The MEMS structures act merely as sensors of, and modulatorsof, this force. This approach allows the realization ofthree-dimensional control of the volume of digital clay with forcesexceeding that of small, distributed actuators, and eliminates the needfor electrical wiring through the volume of the digital clay.

Processing system 110 is illustrated for convenience as having at leasta processor unit 112, a monitor 114 and a keyboard 116. Processingsystem 110 controls the execution of a program, described herein,employed by the present invention. It is understood that any suitableprocessor system 110 may be employed in various embodiments of a digitalclay device. Processing system 110 may be a specially designed and/orfabricated processing system, or a commercially available processingsystem. Non-limiting examples of commercially available processorsystems include, but are not limited to, an 80×86 or Pentium seriesmicroprocessor from Intel Corporation, U.S.A., a PowerPC microprocessorfrom IBM., a Sparc microprocessor from Sun Microsystems, Inc., a PA-RISCseries microprocessor from Hewlett-Packard Company, or a 68xxx seriesmicroprocessor from Motorola Corporation.

Processing system 110 is coupled to a plurality of MEMS valves andsensors of each cell 104, as described in greater detail below, viaconnection 118. Connection 118, for convenience, is illustrated as asingle connection. However, it is understood that connection 118includes internally a plurality of connections, thereby providingconnectivity between processor system 110 and other discrete devicessuch as the MEMS valves, sensors, or a suitable interface bus residingin the backplate 102.

In the embodiment illustrated in FIG. 1A, movement of the digital claysurface 108 is along one axis of movement, namely up or down, based uponthe orientation of the digital clay surface 108 as illustrated in FIG.1A. It is understood that the digital clay surface 108 may be orientedin any desirable manner.

The cell array 106 includes a plurality of columns of cells 120, 122,124 through 126. Cells 120, 122, 124 through 126 each include a bladderconfigured to hold a fluid and a skeleton configured to direct forcesassociated with changes in volume of the bladder, as described ingreater detail below. The bottom of cell 120 is supported by a portionof the backplate 102. Cells 122, 124 through 126 are stacked on top ofcell 120. Cell 126, the top cell of a column of cells (comprised of aplurality of cells) is in contact with a skeleton structure portion 128,described in greater detail below. The skeleton structure portion 128 isin contact with the digital clay surface 108.

When fluid is added to one or more of the plurality cells 120, 122, 124through 126, the skeleton structure portion 128 of the digital claysurface 108 is moved upwards in the direction illustrated by arrow 130.When fluid is removed from one or more of the cells 120, 122, 124through 126, the skeleton structure portion 128 in contact with thedigital clay surface 108 is moved downwards in the direction illustratedby arrow 130. Accordingly, it is understood that the position of theskeleton structure portion 128 is controlled by adding or removing fluidin the cells 120, 122, 124 through 126. Furthermore, it is understoodthat the position of the skeleton structure portion 128 is determined bydetermining the amount of fluid in the cells 120, 122, 124 through 126.Adding, removing and determining the amount of fluid in the cells 120,122, 124 through 126 according to the present invention is described ingreater detail below.

It is understood that the cell array 106 is comprised of a plurality ofcolumns of cells. The top cell of each column of cells is in contactwith a portion of the digital clay surface 108. Thus, the position ofany individual portion of the digital clay surface 108 is determinableand/or controllable since the amount of fluid in each one of the cellsin a cell column is determinable and/or controllable. Accordingly, it isfurther understood that the shape, position and contours of the entiredigital clay surface 108 is determinable and/or controllable since theindividual portions of the digital clay surface 108 are determinableand/or controllable by its respective cell column.

FIG. 1B is a block diagram of a hand held embodiment of a digital claydevice 140 according to the present invention. Processor system 110controls the digital clay device 140 as described herein. Digital claydevice 140 includes a matrix of cells 142, each cell having bladders anda skeleton structure as described herein. The matrix of cells 142extends out to the digital clay surface 144. The shape, size, elasticityand texture of the digital clay surface 144 can be selected to suit aparticular embodiment. For convenience, a portion of the digital claysurface 144 is illustrated as being cut away to show an interior region146 of the digital clay device 140.

For each portion of the digital clay surface 144, a cell portion 148 ofa cell 150 is in contact with the portion of the digital clay surface144. Thus, position of the portion of the digital clay surface 144 isdeterminable and/or controllable according to the present invention.

FIG. 2 is a block diagram of an embodiment of a cell 200. Cell 200includes a bladder 202, a skeleton structure portion 204, MEMS valves206 and 208, sensors 210 and 212, pipes 214 and 216, and a portion 218of backplate 102. MEMS valves 206 and 208, and sensors 210 and 212, arefabricated/mounted on or into the portion 218 of backplate 102. Sensor210, coupled to MEMS valve 206 via connection 220, is configured tosense information corresponding to the amount of fluid passing throughMEMS valve 206. Similarly, sensor 212, coupled to MEMS valve 208 viaconnection 222, is configured to sense information corresponding to theamount of fluid passing through MEMS valve 208.

MEMS valve 206 is coupled to high pressure reservoir 224 via a channel226 and a pipe 228. Channel 226 is fabricated into backplate 102 and iscoupled to MEMS valve 206. Channel 226, pipe 228, MEMS valve 206 andpipe 214 communicate fluid from the high pressure reservoir 224 to thebladder 202 when MEMS valve 206 is open. Accordingly, it is understoodthat pressure of bladder 202 is less than the pressure of the highpressure reservoir 224. In an alternative embodiment, high pressurereservoir 224 is directly coupled to channel 226 such that pipe 228 isomitted.

Similarly, MEMS valve 208 is coupled to low pressure reservoir 230 via achannel 232 and a pipe 234. Channel 232 is fabricated into backplate 102and is coupled to MEMS valve 208. Channel 232, pipe 234, MEMS valve 208and pipe 216 communicate fluid from the bladder 202 to the low pressurereservoir 230 when MEMS valve 208 is open. Accordingly, it is understoodthat pressure of bladder 202 is greater than the pressure of the lowpressure reservoir 230. In an alternative embodiment, low pressurereservoir 230 is directly coupled to channel 232 such that pipe 234 isomitted.

For convenience, an optional bus 238 is illustrated as providingconnectivity between connection 118 and connections 238, 240, 242 and244. In one embodiment, a second processor system 246 is coupled to bus238, via connection 248, to facilitate management of communication ofcontrol signals and/or information between processor system 110 and MEMSvalves 206 and 208, and sensors 210 and 212. The bus 238 and/or thesecond processing unit 246 may be fabricated into the backplate 102 orreside as an external component, depending upon the embodiment. Inanother embodiment, the second processor 246 is omitted such that MEMSvalves 206 and 208, and sensors 210 and 212, are in direct communicationwith the processor system 110. Similarly, in another embodiment, bus 238is omitted such that MEMS valves 206 and 208, and sensors 210 and 212,are in direct communication with the processor system 110 (and/or thesecond processor system 246 if included).

Accordingly, when the bladder 202 is to be expanded (increase volume), asuitable control signal is communicated by processor system 110 to MEMSvalve 206, thereby causing MEMS valve 206 to open. Sensor 210 senses thevolume of fluid passing through MEMS valve 206 and communicates theinformation to processor system 110. When a desired amount of fluid istransported into bladder 202, a suitable control signal is communicatedby processor system 110 to MEMS valve 206, thereby causing MEMS valve208 to close. As described above, expansion of bladder 202 when fluid isadded causes an associated force to be exerted such that the moveableportions 250 of the bladder 202 causes a portion of the digital claysurface to move in a controlled direction.

Similarly, when the bladder 202 is retracted (decrease volume), asuitable control signal is communicated by processor system 110 to MEMSvalve 208, thereby causing MEMS valve 208 to open. Sensor 212 senses thevolume of fluid passing through MEMS valve 208 and communicates theinformation to processor system 110. When a desired amount of fluid istransported from bladder 202, a suitable control signal is communicatedby processor system 110 to MEMS valve 208, thereby causing MEMS valve208 to close. As described above, retraction of bladder 202 when fluidis removed causes an associated force to be exerted such that moveableportion 250 of the bladder 202 causes a portion of the digital claysurface to move in a controlled direction.

Furthermore, an external force may be exerted on the moveable portion250 of bladder 202, via a skeleton structure portion 204, therebyincreasing pressure in bladder 202. For example, a user may squeeze thedigital clay surface, thereby causing an external pressure on themoveable portion 250 of bladder 202. Sensor 210, sensor 212 or anothersuitable sensor (not shown) detects the change in pressure of bladder202. The information from the sensor is communicated to processor system110 such that the processor system understands that an external force isbeing exerted on the digital clay surface, and that it is desirable toremove (or add) fluid from the bladder 202 such that the digital claydeforms in accordance with the applied external force. Accordingly,processor system 110 communicates a suitable signal to MEMS valve 208such that the MEMS valve 208 opens, thereby allowing fluid to exit fromthe bladder 202. Or, processor system 110 communicates a suitable signalto MEMS valve 206 such that the MEMS valve 206 opens, thereby allowingfluid to enter into the bladder 202. When the sensor 210, sensor 212 orother suitable sensor detects a return of bladder pressure to apredetermined value and/or pressure change, and such correspondinginformation is communicated to processor system 110, a suitable controlsignal is communicated such that the opened MEMS valve 208 or 206 isclosed.

FIG. 3 is a block diagram of an alternative embodiment of a cell 300.Cell 300 includes a bladder 302, a skeleton 304, a two-way MEMS valve306, a sensor 308, a pipe 310, and a portion 312 of backplate 102. MEMSvalve 306 and sensor 308 are fabricated/mounted on or into the portion312 of backplate 102. Sensor 308, coupled to MEMS valve 306 viaconnection 314, is configured to sense information corresponding to theamount of fluid passing through MEMS valve 306.

MEMS valve 306 is coupled to high pressure reservoir 224 via a channel226 and a pipe 228. Channel 226 is fabricated into backplate 102 and iscoupled to MEMS valve 306. Channel 226, pipe 228, MEMS valve 306 andpipe 310 communicate fluid from the high pressure reservoir 224 into thebladder 302 when MEMS valve 306 is open in a first position.Accordingly, it is understood that pressure of bladder 302 is less thanthe pressure of the high pressure reservoir 224. In an alternativeembodiment, high pressure reservoir 224 is directly coupled to channel226 such that pipe 228 is omitted.

Similarly, MEMS valve 306 is coupled to low pressure reservoir 230 via achannel 232 and a pipe 234. Channel 232 is fabricated into backplate 102and is coupled to MEMS valve 306. Channel 232, pipe 234, MEMS valve 306and pipe 310 communicate fluid from the bladder 302 to the low pressurereservoir 230 when MEMS valve 306 is open in a second position.Accordingly, it is understood that pressure of bladder 302 is greaterthan the pressure of the low pressure reservoir 230. In an alternativeembodiment, low pressure reservoir 230 is directly coupled to channel232 such that pipe 234 is omitted.

For convenience, an optional bus 238 is illustrated as providingconnectivity between connection 118 and connections 316 and 318. Inanother embodiment, a second processor system 246 is coupled to bus 238,via connection 248, to facilitate management of communication of controlsignals and/or information between processor system 110 and MEMS valve306 and sensor 308. The bus 238 and/or the second processing unit 246may be fabricated into the backplate 102 or reside as an externalcomponent, depending upon the embodiment. In another embodiment, thesecond processor 246 is omitted such that MEMS valve 306 and sensor 308are in direct communication with the processor system 110. Similarly, inanother embodiment, bus 238 is omitted such that MEMS valve 306 andsensor 308 are in direct communication with the processor system 110(and/or the second processor system 246 if included).

Accordingly, when the bladder 302 is expanded (increase volume), asuitable control signal is communicated by processor system 110 to MEMSvalve 306, thereby causing MEMS valve 306 to open in the first position.Sensor 308 senses the volume of fluid passing through MEMS valve 306 andcommunicates the information to processor system 110. When a desiredamount of fluid is transported into bladder 302, a suitable controlsignal is communicated by processor system 110 to MEMS valve 306,thereby causing MEMS valve 306 to close. As described above, expansionof bladder 302 when fluid is added causes an associated force to beexerted such that the moveable portions 320 of the bladder 302 causes aportion of the digital clay surface to move in a controlled direction.

Similarly, when the bladder 302 is retracted (decrease volume), asuitable control signal is communicated by processor system 110 to MEMSvalve 306, thereby causing MEMS valve 306 to open in a second position.Sensor 308 senses the volume of fluid passing through MEMS valve 306 andcommunicates the information to processor system 110. When a desiredamount of fluid is transported from bladder 302, a suitable controlsignal is communicated by processor system 110 to MEMS valve 306,thereby causing MEMS valve 306 to close. As described above, retractionof bladder 302 when fluid is removed causes an associated force to beexerted such that moveable portion 320 of the bladder 302 causes aportion of the digital clay surface to move in a controlled direction.

Furthermore, an external force may be exerted on the moveable portion320 of bladder 302, thereby increasing pressure in bladder 302. Forexample, a user may squeeze the digital clay surface, thereby causing anexternal pressure on the moveable portion 320 of bladder 302. Sensor 308or another suitable sensor (not shown) detects the change in pressure ofbladder 302. The information from the sensor 308 is communicated toprocessor system 110 such that the processor system understands that anexternal force is being exerted on the digital clay surface, and that itis desirable to remove (or add) fluid from the bladder 302 such that thedigital clay deforms in accordance with the applied external force.Fluid would be added to bladder 302 when bladder pressure decreases, andremoved from bladder 302 when bladder pressure increases. Accordingly,processor system 110 communicates a suitable signal to MEMS valve 306such that the MEMS valve 306 opens, thereby allowing fluid to exit fromthe bladder 302. Or, processor system 110 communicates a suitable signalto MEMS valve 306 such that the MEMS valve 306 opens, thereby allowingfluid to enter into the bladder 302. When the sensor 308 or othersuitable sensor detects a return of bladder pressure to a predeterminedvalue and/or pressure change, and such corresponding information iscommunicated to processor system 110, a suitable control signal iscommunicated such that the opened MEMS valve 306 is closed.

In alternative embodiments, the second processor system 246 (FIGS. 2 and3) is configured to receive general instructions relating to the controlof individual bladders and/or bladder units from processor system 110.The second processor system 246 then determines and communicatessuitable control signals to individual MEMS valves to add or removefluids from individual bladders.

Furthermore, in another embodiment, the second processor system 246 isconfigured to receive information from individual sensors and todetermine changes in fluid volumes in the corresponding individualbladders. Corresponding changes in position of the skeleton structureportions, as described in greater detail below, is determined andcommunicated to the processor system 110.

For convenience, sensors 210, 212 and 308 (FIGS. 2 and 3) areillustrated and described above as a generalized, non-specific type ofsensor. Any suitable sensor may be used that provides information suchthat the changes in bladder fluid volume are determinable. In oneembodiment, a sensor is configured to directly measure the fluid volumeflow through a MEMS valve. In another embodiment, a sensor is configuredto directly measure fluid flow rate through a MEMS valve. With thissensor, the change in fluid volume is determined by the integral of thesensed fluid flow rates during the time that the MEMS valve is open. Inyet another embodiment, a sensor is configured to directly measurepressure differences across a MEMS valve. With this sensor, the changein fluid volume is determined by the integral of the sensed pressuredifference to compute a flow rate during the time that the MEMS valve isopen. Other embodiments employ other suitable sensors.

Skeleton structure portions 204 (FIG. 2) and 304 (FIG. 3) are comprisedof at least one rigid skeleton portion. The rigid portion of theskeleton structure portions 204 and 304 restrain movement of thebladders 202 (FIG. 2) and 302 (FIG. 3) when the portions of the bladders202 and 302 are in contact with the rigid portions of the skeletonstructure portions 204 and 304. Thus, the bladders 202 and 302 movewithin the skeleton in the unrestrained direction(s) as fluid is removedfrom or added to the bladders 202 and 302. That is, skeleton structureportions 204 and/or 304 constrain movement of the bladders 202 and 302to a desired direction(s) when the volume of the bladders 202 and 302 ischanged.

In the digital clay device, the skeleton structure portions areselectively coupled together. Coupling may be either rigidly orflexibly. That is, flexible joints or hinges may be used to couple theskeleton structure portions. Accordingly, it is understood that askeleton having a plurality of skeleton structure portions is used toprovide a skeleton that moves in a predictable manner. And, the positionof the individual skeleton portions define the shape of the skeleton.Movement of the skeleton is definable by changes in the position ofskeleton members.

Various control signals and information signals communicated from and/orto processor system 110 are processed by the digital clay logic 252residing in the processor system 110. If a second processor system 246is employed to coordinate communication of signals, and/or generatecontrol signals, as described herein, a portion of the digital claylogic 252 may reside in the second processor system 246.

Another embodiment of a MEMS valve is configured to open when a pressuredifferential across the MEMS valve exceeds a predetermined pressuredifference. The MEMS valve, in one embodiment, is controlledmechanically by the pressure difference. In another embodiment, the MEMSvalve is controlled electronically based upon sensed pressuredifferences. Accordingly, if an external force applied to a bladderincreases bladder pressure, and the resultant pressure differenceexceeds the predefined pressure difference, the MEMS valve opens toallow fluid to flow from the bladder to the low pressure reservoir 230.Similarly, if an external force applied to a bladder decreases bladderpressure, and the resultant pressure difference exceeds the predefinedpressure difference, the MEMS valve opens to allow fluid to flow fromthe high pressure reservoir 224 into the bladder.

Furthermore, rate of change information in the bladder pressures,generated by external forces, may be determined. This determined rate ofpressure change allows determination of the rate of change of theskeleton portions, and accordingly, allows determination of the rate ofchange of the digital clay device surface.

FIG. 4A illustrates an exemplary cell bladder 402 and skeleton structureportion 404 embodiment. For convenience, bladder 402 is illustrated as acylindrical shape. Two pipes 214 and 216 (see also FIG. 2) areillustrated. As described above, pipes 214 and 216 provide for thetransfer of fluid into and out of the cell 402, as described above forcell 200 (FIG. 2). For convenience, skeleton structure portion 404 isillustrated as being shaped as a tube. Skeleton structure portion 404includes an outer wall 406 and an inner wall 408. The diameter of theinner wall 408 is approximately the same diameter of the bladder 402.For illustrative purposes, a portion of the skeleton structure portion404 is illustrated as having a cut-away section 410. (Accordingly, nonvisible portions of the bladder 402 and the skeleton structure portion404 are denoted with dashed lines.)

Thus, as fluid is added to bladder 402, the portion 412 of bladder 402in contact with the inner wall 408 is kinematically constrained frommoving in an outward direction (normal to the inner wall 408). Thus, asthe bladder expands, the top surface 414 of bladder 402 moves in anupward direction (assuming that the bottom of bladder 402 isconstrained), as indicated by the arrow 416. Similarly, as the bladderdeflates, the top surface 414 of bladder 402 moves in a downwarddirection (assuming that the bottom of bladder 402 is constrained), asindicated by the arrow 416.

Top surface 414 is illustrated as being in contact with a member 418.Member 418 is illustrated as being in contact with a skeleton structureportion 420. Thus, movement of the top surface 414 in the upwarddirection (when fluid is added into bladder 402) causes the skeletonstructure portion 420 to move upward by a corresponding amount.Similarly, movement of the top surface 414 in the downward direction(when fluid is removed from bladder 402) causes the skeleton structureportion 420 to move downward by a corresponding amount.

The simplified bladder 402 and skeleton structure portion 404, and theirassociated components, as described above and illustrated in FIG. 4A,demonstrate selected aspects of the present invention. That is, movementof a bladder within a separate skeleton can control movement of a remotesurface. Furthermore, for simplicity, a member 418 was used toillustrate one possible way to couple the skeleton structure portion 420to the bladder 402. Alternative embodiments may use multiple memberscoupled to a plurality of digital clay surface portions. Or, the topsurface 414 may be in direct contact with the skeleton structure portion420 (assuming that the skeleton structure portion 404 is configuredappropriately). Also, the member 418 is illustrated as representing adowel, rod, bar of the like. It is understood that the member may beconstructed of any suitable material and may have any suitableconfiguration without departing substantially from the presentinvention. Thus, the member 418 may be a composite material, a rigidmaterial, or even a semi-rigid material. In one embodiment, member 418and skeleton structure portion 420 are fabricated as a single unit, orfabricated together as a portion of a complex skeleton structure.

Another aspect of the simplified bladder 402 and skeleton structureportion 404 is that for convenience, the simplified bladder 402 andskeleton structure portion 404 were illustrated as a having acylindrical shape. It is understood that the simplified bladder 402 andskeleton structure portion 404 may have any suitable shape. For example,the simplified bladder 402 and skeleton structure portion 404 may have aplurality of flat sides, such as a triangle, square, hexagon or othersuitable multiple sided shape to facilitate the fabrication of a cellmatrix having a plurality of adjacent cells (bladders 402, skeletonstructure portions 404 and associated components). Furthermore, portionsof the simplified bladder 402 and/or skeleton structure portion 404 maybe curvilinear.

Also, it is understood that a unitary body skeleton 422 configured tokinematically restrain movement of a plurality of bladders may beconstructed. FIG. 4B illustrates one such embodiment, wherein theskeleton 422 is configured to restrain many bladders (not shown)residing in cavities 424. Thus, individual walls 426 of the skeleton 422restrain multiple bladders.

With the simplified bladder 402 and skeleton structure portion 404, andtheir associated components, as described above and illustrated in FIG.4A, range of movement of the skeleton structure portion 420 afforded bythe movement of the top surface 414 is ultimately limited by the maximumvolume of fluid that can be added to or removed from bladder 402. Whenbladder 402 and skeleton structure portion 404 are fabricated usingmicro technologies described herein, the range of movement provided by asingle bladder 402 is not perceptible by a user of the digital claydevice.

FIG. 4C illustrates an embodiment of a bladder unit 430 employing aplurality of stacked bladders 432A–D. It is understood that the stackedbladders 432A–D are illustrated for convenience as being shaped in acylindrical form, similar to bladder 402 (FIG. 4A). Accordingly,bladders 432A–D are configured to fit together within the skeletonstructure portion 404 (FIG. 4A) to form bladder unit 430. Thus, thetotal range of movement that may be imparted onto the skeleton structureportion 420 equals the sum of the individual range of motion for eachone of the bladders 432A–D. It is understood that any desirable numberof bladders may be used in a bladder unit. Furthermore, it is understoodthat bladders 432A–D may be shaped to fit within any type of skeleton.For example, but not limited to, the bladders 432A–D could be shaped soas to reside in one of the cavities 424 of skeleton 422 (FIG. 4B).

Also, the bladders 432A–D are illustrated as employing a single pipe 310configured to transfer fluid into or out of its respective bladder, asdescribed above in the embodiment illustrated in FIG. 3. Thus, it isunderstood that for any of the bladder embodiments, skeleton embodimentsand or combined bladder-skeleton embodiments described herein, thatfluids may be transferred into or removed from using the embodimentsdescribed in FIGS. 2 and/or 3.

Skeleton structure portions 204 (FIG. 2) and 304 (FIG. 3), and bladders202 and 302, respectively, are illustrated for convenience as beingseparate components. FIG. 4D is a perspective view of an embodimentwherein the bladder and the skeleton are formed as a singlebladder-skeleton unit 440. Bladder-skeleton unit 440 is illustrated forconvenience as employing a single pipe 310 configured to transfer fluidinto or out of its respective bladder, as described above in theembodiment illustrated in FIG. 3. Another bladder-skeleton unit 440embodiment transfers fluids into or from using the bladder-skeleton unit440 as described in FIG. 2.

Bladder-skeleton unit 440 has eight sides; a top side 442, a bottom side444 (hidden from view), an upper right-hand side 446, a lower right-handside 448 (hidden from view), an upper left-hand side 450, a lowerright-hand side 452 (hidden from view), a front side 454 and a back side456 (hidden from view). The front side 454 and the back side 456 areflexible, but are restrained to moving (stretching) in directions normalto the other sides 442, 444, 446, 448, 450 and 452. (That is, the frontside 454 and the back side 456 do not bulge substantially inward oroutward when fluid is added to or removed from the bladder-skeleton unit440.)

In this embodiment, sides 442, 444, 446, 448, 450 and 452 are rigid, orrelatively rigid. Adjacent sides are coupled together as shown with ahinging device 460. Thus, a hinge 458 couples the upper right-hand side446 to the lower right-hand side 448. Similarly, a hinge 460 couples theupper left-hand side 450 and the lower left-hand side 452, a hinge 462couples the top side 442 with the upper right-hand side 446, and a hinge464 couples the top side 442 with the upper left-hand side 450. It isunderstood that two similar hinges couple the bottom side 444 to thelower right-hand side 448 and to the lower right-hand side 452.Accordingly, as fluid is added to or removed from the bladder-skeletonunit 440, the top side 442 and/or the bottom side 444 move in an upwardsor downwards direction, as indicated by the direction arrow 468.Depending upon the particular digital clay device 100 in which thebladder-skeleton unit 440 is used, the top side 442 or the bottom side444 may be fixed to a rigid structure, thereby limiting movement to theopposing side.

For example, as fluid is added into the bladder-skeleton unit 440, thetop side 442 is forced to move in an upwards direction (particularly ifthe bottom side is in a fixed position). Thus, the angle 470 (formed bythe joining of the upper right-hand side 446 to the lower right-handside 448) and the angle 472 (formed by the joining of the upperleft-hand side 450 to the lower left-hand side 452) increase.Concurrently, the angles 474 (formed by the joining of the other sidesas shown) decrease.

Similarly, as fluid is removed from the bladder-skeleton unit 440, thetop side 442 is forced to move in a downwards direction (particularly ifthe bottom side is in a fixed position). Thus, the angle 470 and theangle 472 decrease. Concurrently, the angles 474 increase.

During fabrication, as described in greater detail below, a plurality ofbladder-skeleton units 440 may be fabricated together. In such anembodiment, resulting in a honey comb-like skeleton matrix, a large cellmatrix is formed. Thus, such an embodiment employing a plurality ofbladder-skeleton units 440 can be fabricated to form any desired shape,form or size. Also, bladder-skeleton units may be formed having anysuitable number of sides and/or curvilinear surfaces.

FIG. 4E illustrates an embodiment employing a bladder unit 476 and askeleton unit 478. Bladder unit has at least one bladder (as indicatedby the pipe 310). A bladder unit 476 may have a plurality of bladdersand be constructed in accordance with any of the embodiments describedherein.

Skeleton unit 478 has a first member 480 and a second member 482,forming an angle 484 therebetweeen. A hinge 486 allows the two members480 and 482 to move, thereby changing the angle 484. It is understoodthat the bladder unit 476 controls the position of the members 480 and482. Thus, when the bladder unit 480 is extended when fluid is addedinto the bladder, as shown by the direction arrow 488, angle 484increases. Similarly, when fluid is removed from the bladder unit 476such that the bladder retracts, angle 484 decreases.

Skeleton unit 478 is a simplified, non-limiting example of a componentthat provides for angular control of two members 480 and 482. Members480 and 482 may have any suitable form, such as, but not limited to,bars, rods, plates, curvilinear surfaces, or even object surfaces.Furthermore, it is understood that the skeleton unit 478 may be aportion of a larger integrated skeleton structure used in a digital claydevice.

FIG. 4F illustrates an embodiment employing a plurality of bladder units430 (see also FIG. 4C) to control a linear skeleton structure 490.Linear skeleton structure 490 is comprised of a plurality of members492. Each member 492 is coupled together as shown at point 494. Point494 is a flexible connector, such as a pin or flexible portion of acontinuous structure, as described in greater detail herein.

As described above, optional members 418 couple the top of the bladderunit 430 to a point 494. As fluid is added to the bladders of bladderunit 430, an upward force is exerted onto its respective point 494 suchthat the position of the respective coupled members 492 is moved upward,as indicated by the direction arrow 496. Similarly, as fluid is removedfrom the bladders of bladder unit 430, a downward force is exerted ontoits respective point 494 such that the position of the respectivecoupled members 492 is moved downward, as indicated by the directionarrow 496. Also, if an external downward force is applied to any member492, the linear skeleton structure 490 and positions of the individualmembers 492 are moved such that a corresponding force is generated onthe respective bladder unit 430. The force on the bladder unit 430causes fluid to be expelled, as described above, such that the newpositions of the members 492 are determinable.

Therefore, it is understood that the shape of the linear skeletonstructure 490, and the position of any individual member 492, iscontrollable by the bladder units 430 according to the presentinvention. Furthermore, deformations in the shape of the linear skeletonstructure 490, or changes in the position of any individual member 492,caused by an external force is determinable by the present invention.

When a plurality of linear skeleton structures 490 are alignedside-by-side to from an array, a surface is defined. The surface may bepart of a table top embodiment similar to the embodiment illustrated inFIG. 1A, or may be part of the surface of a volume of digital clay.Furthermore, the top of the plurality of linear skeleton structures 490may be covered with a flexible digital clay surface 108 (FIG. 1A).

Additionally, as described above, it is understood that each one of thebladder units 430 is associated with its own skeleton (not shown) suchthat when fluid is added or removed from individual bladders, forces andmovement are generated along the direction shown by the direction arrow496. Furthermore, the skeletons associated with each of the bladderunits 430 and the linear skeleton structure 490 may be formed into asingle unitary skeleton structure when the digital clay device isfabricated.

FIG. 4G illustrates an embodiment employing a plurality of bladder units430 (see also FIG. 4C) to control a skeleton structure portion 497.Skeleton structure portion 497 is comprised of a plurality of points 498and optional members 499. Points 498 are comprised of a flexibleconnector providing for multiple degrees of freedom of movement, such asa pin or flexible portion of a continues structure, as described ingreater detail herein.

For convenience, the skeleton structure portion 497 is illustrated as arectangular structure having eight points 498. However, it is understoodthat the skeleton structure may have any number of points 498, therebycreating a skeleton structure portion 497 of any desirable size orshape. Also, for convenience, points 498 are illustrated as cubicstructures. The points 498 may be formed in any suitable shape orconfiguration. Furthermore, the bladder units are illustrated forconvenience as being coupled to the cube shaped points 498 in adirection normal to the faces of the cube shaped points 498. It isunderstood that bladder units 430 may be connected across diagonals ofthe skeleton structure portion 497, or even between non-adjacent points498 (when a larger matrix of points 498 comprise the skeleton structureportion 497). Accordingly, the selection of the points 498 with abladder unit 430 is a preference made at the time of design and/orfabrication of the skeleton structure portion 497.

In one embodiment, the outside surface of skeleton structure portion497, or portions thereof, is covered with a digital clay surface 108(FIG. 1A). As noted above, the elasticity and texture of the digitalclay surface 108 can be selected to suit a particular embodiment.

As illustrated in FIG. 4G, a point 498 is coupled to one or more bladderunits 430. Thus, it is understood that the position of any point iscontrollable and/or determinable by embodiments of the presentinvention. As described above, optional members 499 couple the ends ofthe bladder units 430 to a point 498. As fluid is added to the bladdersof bladder unit 430, a force is exerted onto its respective point 498such that the position of the respective point 498 is moved. Similarly,as fluid is removed from the bladders of bladder unit 430, a force isexerted onto its respective point 498 such that the position of thepoint 498 is moved. Furthermore, if an external force is applied to anypoint 498, the skeleton structure portion 497 and positions of thepoints 498 are moved such that a corresponding force is generated on therespective bladder units 430. The force on the bladder units 430 causesfluid to be expelled, as described above, such that the new positions ofthe points 498 are determinable.

The various embodiments of the skeleton structure(s) described hereinprovide kinematic constraints to the motion of the bladders and/orbladder units in the digital clay device. Measurement of the volume offluid in each bladder, along with a solution of the kinematics of theskeleton structure, allows the unambiguous determination of the positionof the outermost surface of the digital clay device, thereby leadingexternally to a predictable digital clay surface shape.

The skeleton structure, in one embodiment, is formed from a scaffoldingstructure fabricated using stereolithorgraphy (SLA). The skeletonstructure is fabricated to support active and passive motion in a verylarge number of degrees of freedom. Thus, the skeleton structure is a3-D deformable structure. A SLA scaffolding structure employs a processof building the 3-D skeleton structure by selectively curingphotopolymer with an ultraviolet (UV) laser. Accordingly, a skeletonstructure fabricated using SLA technologies includes the capability tobuild portions of the skeleton using any desired arbitrary shape.Intricate interior structures wherein bladders, pipes and skeletonportions may be fabricated as a unit. Also, a skeleton structurefabricated using SLA technologies implements compliant (flexible) joints(hinges) by varying the thickness of interior connections in theskeleton structure. Furthermore, a skeleton structure fabricated usingSLA technologies provides for the insertion of sensors during theskeleton structure fabrication process in another embodiment.

As described herein, the skeleton structure may be configured using anysuitable geometry. Simplified, non-limiting illustrative geometries havebeen described above in FIGS. 4A–G, and elsewhere herein. Very complexgeometries may be used to form the skeleton structure (or portionsthereof). One embodiment employs a variable geometry truss (VGT). A VGTis a truss structure that actively deforms by changing the lengths ofselected links. Accordingly, a skeleton structure employing VGT portionsprovides for folding structure portions that are easily deformed. Forexample, but not limited to, a VGT comprised of stacked octahedral trussstructures can be completely folded away by actuating the length ofselected lateral members by a small amount. Such a VGT structureemployed in a digital clay device is advantageous since a small bladdermovement results in a very large change of digital clay volume, thusallowing the digital clay device to undergo very large deformations.

FIGS. 5 and 6 are flow charts 500 and 600, respectively, illustratingprocesses used by an embodiment of the digital clay device to adjust theposition of a skeleton structure portion. The flow charts 500 and 600show the architecture, functionality, and operation of a possibleimplementation of the software for implementing the digital clay logic252 (FIGS. 2 and 3). In this regard, each block may represent a module,segment, or portion of code, which comprises one or more executableinstructions for implementing the specified logical function(s). Itshould also be noted that in some alternative implementations, thefunctions noted in the blocks may occur out of the order noted in FIGS.5 and/or 6, and/or may include additional functions, without departingsignificantly from the functionality of the present invention. Forexample, two blocks shown in succession in FIGS. 5 and/or 6 may in factbe executed substantially concurrently, the blocks may sometimes beexecuted in the reverse order, or some of the blocks may not be executedin all instances, depending upon the functionality involved, as will befurther clarified hereinbelow. All such modifications and variations areintended to be included herein within the scope of this disclosure forthe digital clay device and to be protected by the accompanying claims.

The flow chart 500 of FIG. 5 starts at block 502. At block 504 a desiredposition of a skeleton structure portion residing in the digital claydevice is determined. At block 506 a volumetric change of a fluidresiding in a bladder, the determined volumetric change corresponding tothe determined desired position of the skeleton structure portion, isdetermined. At block 508 a control signal corresponding to thedetermined volumetric change is generated. At block 510 the controlsignal is communicated to a MEMS valve such that the MEMS valve opens sothat the fluid flows through the MEMS valve thereby causing thedetermined volumetric change of the fluid residing in the bladder. Atblock 512 the position of the skeleton structure portion is adjustedcorresponding to the desired position of the skeleton structure portion,the position adjustment caused by a force generated by the bladder onthe skeleton structure portion when the volume of the bladder changes inresponse to the determined volumetric change of the fluid residing inthe bladder. The process ends at block 514.

The flow chart 600 of FIG. 6 starts at block 602. At block 604 flow ofthe fluid through the MEMS valve is sensed. At block 606 a measuredvolumetric change in the fluid from the sensed flow is determined. Atblock 608 the measured volumetric change and the determined volumetricchange are compared. At block 610 a second control signal is generatedwhen the measured volumetric change substantially equals the determinedvolumetric change. At block 612 the second control signal iscommunicated to the MEMS valve such that the MEMS valve closes so thatthe fluid flow through the MEMS valve stops. The process ends at block614.

The flow charts 500 and 600 describe processes for controlling flow intoor out of one bladder. It is understood that the processes are equallyapplicable to a selected plurality of bladders. When flow of fluid intoand out of a plurality of selected bladders are controlled in acoordinated manner by the present invention as described above, thevolume and shape of the digital clay device is controllable.

FIG. 7 is a flow chart 700 illustrating processes used by an embodimentof the digital clay device to sense the position of a skeleton structureportion. The flow chart 700 shows the architecture, functionality, andoperation of a possible implementation of the software for implementingthe digital clay logic 252 (FIGS. 2 and 3). In this regard, each blockmay represent a module, segment, or portion of code, which comprises oneor more executable instructions for implementing the specified logicalfunction(s). It should also be noted that in some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in FIG. 7 and/or may include additional functions withoutdeparting significantly from the functionality of the present invention.For example, two blocks shown in succession in FIG. 7 may in fact beexecuted substantially concurrently, the blocks may sometimes beexecuted in the reverse order, or some of the blocks may not be executedin all instances, depending upon the functionality involved, as will befurther clarified hereinbelow. All such modifications and variations areintended to be included herein within the scope of this disclosure forthe digital clay device and to be protected by the accompanying claims.

The flow chart 700 of FIG. 7 starts at block 702. At block 704 aninitial position of a skeleton structure portion residing in the digitalclay device is determined. The initial position can be determined from apredefined position that the skeleton structure portion has been presetto prior to application of an external force. Or, the initial positioncan be determined from a prior state.

At block 706 a pressure change on a bladder, the pressure changecorresponding to an external force applied to the exterior portion ofthe digital clay device is sensed. At block 708 a MEMS valve is openedin response to the sensed pressure change such that fluid residing inthe bladder exits the bladder. At block 710 flow of the fluid throughthe MEMS valve is sensed. At block 712 the MEMS valve is closed when thesensed pressure is reduced to at least a predefined value such that flowof the fluid through the MEMS valve stops. The reduced pressure resultsfrom the exit of fluid from the bladder. At block 714 a volumetricchange in the fluid from the sensed flow after the MEMS valve is closedis determined. At block 716 a change in the position of the skeletonstructure portion is determined based upon the determining a volumetricchange. The process ends at block 718.

The flow chart 700 describe a process for determining the change inposition of a portion of a skeleton structure based upon flow out of onebladder. It is understood that the process is equally applicable todetermining the change in position of a plurality of skeleton structureportions by sensing flow out of a plurality of bladders. When flow offluid out of a plurality of bladders are sensed in a coordinated mannerby the present invention as described above, the shape of the digitalclay is determinable.

It should be emphasized that the above-described embodiments of thepresent invention are merely possible examples of implementations,merely set forth for a clear understanding of the principles of theinvention. Many variations and modifications may be made to theabove-described embodiment(s) of the invention without departingsubstantially from the spirit and principles of the invention. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and the present invention and protected bythe following claims.

1. A method for controlling shape of a digital clay device, the methodcomprising: determining a desired position of a skeleton structureportion residing in the digital clay device; determining a volumetricchange of a fluid residing in a fluid cell, the determined volumetricchange corresponding to the determined desired position of the skeletonstructure portion; opening a valve so that the fluid flows through thevalve thereby causing the determined volumetric change of the fluidresiding in the fluid cell; and adjusting a position of the skeletonstructure portion corresponding to the desired position of the skeletonstructure portion, the position adjustment caused by a force generatedby the fluid cell on the skeleton structure portion when volume of thefluid cell changes in response to the determined volumetric change ofthe fluid residing in the fluid cell.
 2. The method of claim 1, whereinopening the valve further comprises opening a hysteric valve.
 3. Themethod of claim 1, wherein opening the valve further comprises openingan active valve.
 4. The method of claim 1, wherein opening the valvefurther comprises opening a passive valve.
 5. The method of claim 1,further comprising: sensing flow of the fluid through the valve;determining a measured volumetric change in the fluid from the sensedflow; comparing the measured volumetric change to the determinedvolumetric change; and closing the valve so that the fluid flow throughthe valve stops when the measured volumetric change substantially equalsthe determined volumetric change.
 6. The method of claim 5, whereinsensing flow further comprises sensing a flow rate of the fluid throughthe valve.
 7. The method of claim 5, wherein sensing flow furthercomprises sensing a pressure difference across the valve, and whereindetermining the measured volumetric change further comprises calculatinga flow rate of the fluid through the valve based upon the sensedpressure difference.
 8. The method of claim 1, further comprising:determining a plurality of volumetric changes of fluid residing in aplurality of fluid cells such that the sum of the determined pluralityof volumetric changes corresponds to the determined desired position ofthe skeleton structure portion; opening a corresponding plurality ofvalves so that fluid flows through the valve thereby causing thedetermined volumetric change of the fluid residing in the correspondingfluid cells; sensing flow of fluid through each one of the plurality ofvalves; determining a plurality of measured volumetric changes in thefluid from the sensed flows; comparing each one of the plurality ofmeasured volumetric changes to a corresponding one of the determinedvolumetric changes; and closing the plurality of valves when thecorresponding one of the measured volumetric changes substantiallyequals the corresponding determined volumetric change.
 9. The method ofclaim 1, wherein the opening further comprises opening the valve so thatthe fluid flows through the valve thereby causing fluid to flow into thefluid cell in response to a pressure differential in a reservoir. 10.The method of claim 1, wherein the opening further comprises opening thevalve so that the fluid flows through the valve thereby causing fluid toflow out of the fluid cell into a reservoir.
 11. A method forcontrolling shape of a digital clay device, the method comprising:determining a desired position of a skeleton structure portion residingin the digital clay device; determining a volumetric change of a fluidresiding in a fluid cell, the determined volumetric change correspondingto the determined desired position of the skeleton structure portion;changing volume of the fluid in the fluid cell thereby causing thedetermined volumetric change of the fluid residing in the fluid cell;and adjusting a position of the skeleton structure portion correspondingto the desired position of the skeleton structure portion, the positionadjustment caused by a force generated by the fluid cell on the skeletonstructure portion when the volume of the fluid cell changes in responseto the determined volumetric change of the fluid residing in the fluidcell.
 12. A method for sensing shape of a digital clay device, themethod comprising: determining an initial position of a skeletonstructure portion residing in the digital clay device; sensing apressure change in a fluid cell, the pressure change corresponding to anexternal force applied to an exterior portion of the digital claydevice; opening a valve in response to the sensed pressure change suchthat fluid residing in the fluid cell exits the fluid cell; sensing flowof the fluid through the valve; closing the valve when the sensedpressure change is reduced to at least a predefined value, the reducedpressure change resulting from the exit of fluid from the fluid cell,such that flow of the fluid through the valve stops; determining avolumetric change in the fluid from the sensed flow after the valve isclosed; and determining a change in the position of the skeletonstructure portion based upon the determined volumetric change.
 13. Themethod of claim 12, wherein opening the valve further comprises openinga hysteric valve.
 14. The method of claim 12, wherein opening the valvefurther comprises opening an active valve.
 15. The method of claim 12,wherein opening the valve further comprises opening a passive valve. 16.The method of claim 12, wherein sensing pressure change furthercomprises sensing a rate of the pressure change.
 17. The method of claim16, wherein determining the change in the position of the skeletonstructure portion is based upon the sensed rate of the pressure change.18. The method of claim 12, further comprising: determining a pluralityof initial positions for each one of a plurality of skeleton structureportions residing in the digital clay device; sensing a pressure changein a plurality of fluid cells, the pressure change corresponding to theexternal force applied to the exterior portion of the digital claydevice; opening a plurality of valves in corresponding ones of theplurality of fluid cells in response to the sensed pressure change suchthat fluid residing in the fluid cells exits the fluid cells; sensingflow of the fluid through each one of the corresponding valves; closingeach one of the corresponding valves when the sensed pressure change ineach one of the corresponding fluid cells is reduced to at least apredefined value, the reduced pressure change resulting from the exit offluid from the fluid cells; determining volumetric change in the fluidfrom the sensed flow in each one of the corresponding valves after thevalves are closed; and determining change in the position of theskeleton structure portions based upon the determined volumetricchanges.
 19. A method for sensing shape of a digital clay device, themethod comprising: determining an initial position of a skeletonstructure portion residing in the digital clay device; sensing apressure change in a fluid cell, the pressure change corresponding to anexternal force applied to an exterior portion of the digital claydevice; changing a volume of fluid residing in the fluid cell; endingthe volume change of the fluid when the sensed pressure changecorresponds to at least a predefined value, the pressure changeresulting from the volume change of the fluid in the fluid cell;determining a volumetric change in the fluid from the sensed flow afterending the fluid removal; and determining a change in the position ofthe skeleton structure portion based upon the determined volumetricchange.
 20. A system which controls a surface of a digital clay device,comprising: a processor system; a plurality of modules, each one of theplurality of modules further comprising: at least one fluid cell, thefluid cell configured to hold a fluid; at lease one valve, the valvecontrolled by the processor system; and at least one sensor coupled tothe valve, the sensor configured to sense flow of the fluid through thevalve such that a volumetric change of the fluid residing in the fluidcell is determinable by the processor system; and a covering having aplurality of surface portions, the covering being flexible and formingthe surface of the digital clay device, each one of the surface portionscoupled to selected ones of the plurality of modules such that aposition of each one of the plurality of surface portions iscontrollable and determinable, the position of each one of the pluralityof surface portions corresponding to an amount of the fluid residing inthe corresponding fluid cell.
 21. The system of claim 20, wherein thevalve further comprises a hysteric valve.
 22. The system of claim 20,wherein the valve further comprises an active valve.
 23. The system ofclaim 20, wherein the valve further comprises a passive valve.
 24. Thesystem of claim 20, wherein each one of the modules further comprises askeleton structure portion configured to kinematically constrainmovement of the fluid cell in a predetermined direction.
 25. The systemof claim 20, wherein each one of the modules further comprises abackplate portion where the valve and the sensor reside.
 26. The systemof claim 20, wherein at least one of the modules comprises a singlevalve and a single sensor, the single valve configured to open in afirst position such that the fluid flows into the fluid cell, andfurther configured to open in a second position such that the fluidflows out of the fluid cell.
 27. The system of claim 20, furthercomprising a high pressure reservoir, the high pressure reservoir havinga pressure greater than a fluid cell pressure of the fluid cell suchthat when a corresponding valve coupled between the fluid cell and thehigh pressure reservoir is opened, the fluid flows from the highpressure reservoir into the fluid cell.
 28. The system of claim 20,further comprising a low pressure reservoir, the low pressure reservoirhaving a pressure less than a fluid cell pressure of the fluid cell suchthat when a corresponding valve coupled between the fluid cell and thelow pressure reservoir is opened, fluid flows from the fluid cell intothe low pressure reservoir.
 29. A system for sensing shape of a digitalclay device, comprising: means for determining a desired position of askeleton structure portion residing in the digital clay device; meansfor determining a volumetric change of a fluid residing in a fluid cell,the determined volumetric change corresponding to the determined desiredposition of the skeleton structure portion; means for changing thevolume of fluid in the fluid cell thereby causing the determinedvolumetric change of the fluid residing in the fluid cell; and means foradjusting a position of the skeleton structure portion corresponding tothe desired position of the skeleton structure portion, the positionadjustment caused by a force generated by the fluid cell on the skeletonstructure portion when the volume of the fluid cell changes in responseto the determined volumetric change of the fluid residing in the fluidcell.
 30. The system of claim 29, further comprising: means for sensingflow of the fluid; means for determining a measured volumetric change inthe fluid from the sensed flow; and means for comparing the measuredvolumetric change to the determined volumetric change.
 31. The system ofclaim 30, wherein the means for sensing flow further comprises means forsensing a pressure difference across a valve, and wherein the means fordetermining the measured volumetric change further comprises means forcalculating a flow rate of the fluid through the valve based upon thesensed pressure difference.
 32. A computer readable medium having aprogram for sensing shape of a digital clay device, the programcomprising logic configured to perform: determining a desired positionof a skeleton structure portion residing in the digital clay device;determining a volumetric change of a fluid residing in a fluid cell, thedetermined volumetric change corresponding to the determined desiredposition of the skeleton structure portion; communicating a firstcontrol signal to a valve such that the valve opens so that the fluidflows through the valve thereby causing the determined volumetric changeof the fluid residing in the fluid cell; and communicating a secondcontrol signal to the valve such that the valve closes when position ofthe skeleton structure portion adjusts the desired position of theskeleton structure portion, the position adjustment caused by a forcegenerated by the fluid cell on the skeleton structure portion when thevolume of the fluid cell changes in response to the determinedvolumetric change of the fluid residing in the fluid cell.
 33. A systemwhich senses shape of a digital clay device, comprising: means fordetermining an initial position of a skeleton structure portion residingin the digital clay device; means for sensing a pressure change in afluid cell, the pressure change corresponding to an external forceapplied to an exterior portion of the digital clay device; means foradjusting volume of a fluid in the fluid cell in response to the sensedpressure change such that fluid residing in the fluid cell exits thefluid cell; means for sensing flow of the fluid from the fluid cell;means for ending flow of the fluid through the fluid cell when thesensed pressure change is reduced to at least a predefined value, thereduced pressure change resulting from the exit of fluid from the fluidcell; means for determining a volumetric change in the fluid afterending the flow of fluid; and means for determining a change in theposition of the skeleton structure portion based upon the determinedvolumetric change of the fluid.
 34. The system of claim 33, furthercomprising means for returning the skeleton structure portion to apredetermined position such that the initial position of the skeletonstructure portion is based upon the predetermined position.
 35. Thesystem of claim 33, further comprising means for retrieving informationcorresponding to a previous position of the skeleton structure portionsuch that the initial position of the skeleton structure portion isbased upon the previous position.
 36. A computer readable medium havinga program for sensing shape of a digital clay device, the programcomprising logic configured to perform: determining an initial positionof a skeleton structure portion residing in the digital clay device;sensing a pressure change in a plurality of fluid cells, the pressurechange corresponding to an external force applied to an exterior portionof the digital clay device; opening at least one valve in response tothe sensed pressure change such that fluid residing in the fluid cellexits the fluid cell; sensing flow of the fluid through the valve;closing the valve when the sensed pressure change is reduced to at leasta predefined value, the reduced pressure change resulting from the exitof fluid from the fluid cell, such that flow of the fluid through thevalve stops; determining a volumetric change in the fluid from thesensed flow after the valve is closed; and determining a change in theposition of the skeleton structure portion based upon the determinedvolumetric change.
 37. A method for controlling shape of a surface usinga digital clay device, the method comprising: determining a desiredposition of at least one surface portion; determining a volumetricchange of a fluid residing in a fluid cell, the determined volumetricchange corresponding to the determined desired position of the surfaceportion; changing volume of the fluid in the fluid cell, thereby causingthe determined volumetric change of the fluid residing in the fluidcell; and adjusting a position of the surface portion corresponding tothe desired position of the surface portion, the position adjustmentcaused by a force generated by the fluid cell when the volume of thefluid cell changes in response to the determined volumetric change ofthe fluid residing in the fluid cell.
 38. The method of claim 37,further comprising: sensing flow of the fluid; determining a measuredvolumetric change in the fluid from the sensed flow; comparing themeasured volumetric change to the determined volumetric change; andending the flow of the fluid.
 39. The method of claim 38, whereinsensing flow further comprises sensing a pressure difference across avalve, and wherein determining the measured volumetric change furthercomprises calculating a flow rate of the fluid through the valve basedupon the sensed pressure difference.
 40. The method of claim 37, furthercomprising: determining a plurality of volumetric changes of fluidresiding in a plurality of fluid cells such that the sum of thedetermined plurality of volumetric changes corresponds to the determineddesired position of the surface portion; changing volume of the fluid inthe plurality of fluid cells thereby causing the determined volumetricchange of the fluid residing in the corresponding fluid cells; sensingflow of fluid of each one of the plurality of fluid cells; determining aplurality of measured volumetric changes in the fluid in the pluralityof fluid cells from the sensed flows; comparing each one of theplurality of measured volumetric changes to a corresponding one of thedetermined volumetric changes; and ending the flow of the fluid when thecorresponding ones of the measured volumetric changes substantiallyequals the corresponding determined volumetric change.
 41. The method ofclaim 37, further comprising: opening a valve to a first position sothat the fluid flows into the fluid cell when the determined volumetricchange increases an amount of fluid residing in the fluid cell; andopening the valve to a second position so that the fluid flows out ofthe fluid cell when the determined volumetric change decreases theamount of fluid residing in the fluid cell.
 42. A method for sensingshape of a surface using a digital clay device, the method comprising:determining an initial position of a surface portion; sensing a pressurechange in a fluid cell, the pressure change corresponding to an externalforce applied to the surface portion; changing volume of the fluid inthe fluid cell; sensing flow of the fluid removed from the fluid cell;ending the fluid flow when the sensed pressure change is reduced to atleast a predefined value, the reduced pressure change resulting from theexit of fluid from the fluid cell; determining a volumetric change inthe fluid from the sensed flow; and determining a change in the positionof the surface portion based upon the determined volumetric change. 43.The method of claim 42, further comprising returning the surface portionto a predetermined position such that determining the initial positionof the surface portion is based upon the predetermined position.
 44. Themethod of claim 42, further comprising retrieving informationcorresponding to a previous position of the surface portion such thatdetermining the initial position of the surface portion is based uponthe previous position.
 45. The method of claim 42, further comprising:determining a plurality of initial positions for each one of a pluralityof surface portions; sensing a pressure change in a plurality of fluidcells, the pressure change corresponding to the external force appliedto the surface portions; changing volume of the fluid in the fluidcells; sensing flow of the fluid through each one of the fluid cells;ending fluid flow when the sensed pressure change in each one of thecorresponding fluid cells is reduced to at least a predefined value, thereduced pressure change resulting from the exit of fluid from the fluidcells; determining a volumetric change in the fluid from the sensedflows; and determining a change in the position of the surface portionsbased upon the determined volumetric changes.